A coroner recorded an open verdict into Mr Lubbock's death following an inquest in September 2002.

The IPCC report revealed that the two pieces of evidence which were not seized by police and subsequently went missing could have been crucial to the case.

The swimming pool thermometer appears in photographs of the scene but, along with the detached door handle, was never forensically tested.

It has not been possible for the police to establish whether or not the implements were used to cause Mr Lubbock's injuries, the IPCC said.

'Lingering fears'

The complaints which were upheld include: the scene not being effectively preserved; unauthorised people allowed to stay at the scene; a member of the public being allowed to take the temperature of the swimming pool, and the investigation being suspended prematurely.

IPCC Commissioner David Petch said: "There are absolutely no grounds to support allegations that officers acted corruptly.

"The view that the entire investigation was incompetent is not borne out by the bulk of the evidence.

"But undoubtedly there were failings in some aspects of the investigation.

"As a consequence there are lingering fears that, because the integrity of the scene was not properly preserved, important evidence may have been lost."

He added: "In our view the decision in December 2001 to suspend the investigation was premature - at that time some key forensic work had not been completed and some inquiries were still outstanding.

"We will probably never know whether the missing thermometer and door handle were evidentially important, but not securing these items was a failure and leaves questions unanswered.

"All of these shortcomings must be frustrating and distressing for Mr Lubbock, who has worked tirelessly to find out what happened to his son."

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